// div-MAIN回到顶部
export const mainScrollTop = (time, num) => {
	let speed = time;
	let main = document.body;
	let scrollHeight = main.scrollTop / num;
	let t = setInterval(() => {
		if(main.scrollTop == 0){
			clearTimeout(t);
		}else{
			main.scrollTop = main.scrollTop - scrollHeight;
		}
	}, speed)
}